Method ob making ventilatrnxx  stbips fob tbansfobmebs



July 24, 1928.

F. H. TUPPER METHOD OFIMAKING VENTILATING STRIPS-FOR THANSFORMERSOriginal Filed April 18. 1922 l WJ.

WKIIHVIIIVIllilllflll U f /H/ f 4 O# i. i /H/ INVENTOR Frank f7. TapperTTORNEY l. beinexpen'siveand'whic rodice uniform results in` quantitylmanucharacters designate like parts,

July 24, 1.928. l. UNITED, STATES PATENT oFFiCl-i.

lFRANK rH. TUPPEB, 0F WILKINSBURG, PENNSYLVANIA, ASSIGNOB 1 0WESTDTGHOUSI ELEC'IBIC MANUFACTURING COMPANY, A CORPORATION 0FPENNSYLVANIA.-

METHOD-0F IAIING-IVENTII4ATING STRIPS FOB 'IBANSI'OBCMCIIZ'.ES.v

Manlio; 1,565,533, 'dated December 15K, 1926, Serial No, 555,181, medApril 1B, 1928. Application for relslue led December 7, 1927. Serial No.238,446.

My invention relates to composite articles, more especially to a methodof joining articles of molded composition embod ing a heat-hardenedbinder, such as a p enolic l, condensation product.

It is among the objects of this invention to.

-provide a bond between two or. 'more of molded articles which shall bemechanically strong 4and Adurable and electrically vellicient' a andwhich shall be "of the saine general physical characteristics as the'articles joined.

Another object of this invention is to provide a method of joiningmolded articles which shall beV simple `to r'actice, which shall iishallbe adapted to yHeretofore, it has been-customary to join compositearticles comprisin fibrous matel0 rial and a heat-'hardened bin er binsertin `such molded'members in a 'suitab e mold o the saine lcontourand shape as the articles to be joined, roughening their surfaces whereit is desired to eect a bond, -coating said I surfaces with a liquidbinder having the characteristic of hardening under heat and pressure,such as a phenohc condensation product, inserting'the mold between apair of heated platens of a hydraulic'press and i0 applying heat andlpressure thereto to form an integral structure. My invention is animprovement over this process in that my method does not I elu re theuse of la mold which has been consi ered 8,5 as necessa tojpreventblistering and dis-v tortion of e surface layers. I have found that, byemployinv relatively low temperatures, as compar with the temperatures lused-instandard practice, I am able to effect .I0 a bond between two or-more 'molded memberswighout causing distortion or blistering thereof. lIn the accom anyin'g drawing constituting a part hereo and in which'li ereference Figure 1 is an exploded view oftwo layers of molded sheetmaterial;

Fi .'2 is a side elevationalview-showing the a ers of 1 joined inaccordance 60 with t is invention;

Fig. 3 is an loded view showin avpair l of'she'ets of mol ed materialand a p urality of strips -of like material; Fig. lis aside elevationalviewshowing the strips and sheets of Fig. 3 joined by molding;

Fig., 5 is a to structure having si and p 6 is a side elevational viewthereof.

plan vvie-w of la similar agonally', disposed strips;

teit is desired to jona plurality'of molded plates `1 and 2 comprising aplurality o f la ers of fibrous sheet material consolidat b aheat-hardened binder, I roughen the sur aces 3 by means of sandpaper orby any foth'er suitable means, apply a coating -of a solution of aphenolic condensation product thereto, join the two pieceswith theircoated surfaces `in enga ement and in- -sei'tjthe'm between a pair ofcated platens of a hydraulic press. A temperature of approximately125 C.and a pressure of approximately one-helften er square inch of engagingsurfacef are applied thereto fora suilicient length of time to ermit thebinder to cure, the article being t en cooled inthe press and removed. y

This much of the process 'diers fromthe method heretofore employed inthat a lower temperature is utilized' which produces a more eiicientbond or joint, and where it is desired to join a plurality of strips 4and layers v5 Vand 6 (Fig. 3), my process will prevent those parts '7and 8 of the surfaoesof, the plates and strips, respectively, which Aandpressure are appliedwithin the limits enumerated above-t0 consolidatethe bled membersl and form an integral v struc- ".ture. l

Ihave found that, by employing a strip of fibrous sheet materialimpregnated with a phenolic condensation product between the members tobe joined, instead of the varnish,

a mechanically stronger joint can be pro :duced but this is notessential excepting {wher-'e strength is the main factor. l They processof molding is the same as thatem- 85 are not-in-contact with thepressure latens, i'

I ployed for the and the resulting product is equivalent in strength andphysical characteristics to one formed of a molded compotion orlaminated material. It will be noted that the layers to be joined ma'becoated with the hinder in several ways. he

. binder may be applied as a varnish and the solvent removed; or a sheetof material may be im regnated with a solution of the bmder and t esolvent removed, and the impregnated sheet may be then applied as acoating between the layers to be joined; or solid binder or compositionsinc uding the same may be placed therebetween to provide the Figs. and 6illustrate an article formed in the above specified manner which is cutinto strips and commonly employed as ventilatin strips in transformerconstruction. It is o vious that a structure of this type can not bemanufactured in a practical and economical manner excepting by themethod lherein described, as, bythe old process, 1t

would be essential to insert metal strips between the molded stripswhile'molding them together to prevent blistering and distortion of thematerial, whereas, by my process, this as the forming of ventilatingstrips and blood glue, or the like. "adapted to join articles of variousshapes ving heat and pressure t general insulating materials having astructural body shape to provide the requislte strength and surfacecontour.

Although I `have described a specific embodimentof my invention, it willbe obvious to those skilled in that art that various modifications maybe made in the details of my mcgsawithout departing from the principlesereln set forth. For instance, my method is adapted to join sheets andstrips of liber, wood and `similar materials, and the binder may be ofany suitable type, such as casein, This process is also and contours andis not limited to flat-surface materials, as illustrated in t-hedrawings. I claim as my invention: 1. A me/thod of joining moldedarticles which comprises roughening the surfaces to. be joined, placinon said rou hened `surfaces a binder w ich is adapte to harden under theiniuence of heat and pressure, inserting said articles in a press withtheir treated' surfacesin .enga ement and applyhereto to forman integralstructure. v

2. A method of joining molded articles which comprises roughening the'surfaces to be joined, placing onsaid roughened surfaces a .phenolic`condensation product, in-

serting said varticles in ai press with their treated" surfaces inengagement and applying heat'and Epressure thereto to form an integralstructure. I

3. Al method of joiningmolded articles which comprises roughening thesurfaces to be joined, placing on said roughened surfaces a phenoliccondensation product, inv serting said articles in a press with theirtreated surfaces in engagement and applying a relatively low temperatureand a high pressure thereto.

4.-. A method of joining molded articles which comprises roughening thesurfaces to be joined, placing on saidroughened surfaces a phenoliccondensation product, in

`be joined, placing en said roughened surfaces a phenolic condensat-ionproduct, inserting said articles in a press with their treated surfacesin engagementv and applying a.- temperature ranging between and 125.'C.thereto. n

6.- A Vmethod of joining. molded articles Awhich comprises rougheningthe surfaces to be joined, placing on said roughened surfaces a phenoliccondensation product, insertin said articles in a press with theirtreate surfaces in engagementand applyin a tem erature ranging between100 and 125 and a pressure of approximately onehalf ton per square inchof molding surface thereto. 1

7. A method of joining molded articles which comprises roughening Vthesurfaces to be joined, interposmg a layer of fibrous sheet material imregnated with a binder between said roughened' surfaces, inserting saidarticles in a. press and ap lylng a relatively low temperature and a 'ghpressure thereto to form an integral structure.k

8. kA method of joining moldedl articles' which comprises roughening thesurfaces to be joined, interposing a. layer of fibrous sheet materialimpregnated with a phenolic condensation product between said roughenedsurfaces, inserting said articles in a pressand applying a relativelylow .temperature` and ahigh pressure theretoto form an integralstructure.

, 9. A method of joining molded articles which comprises roughenlng thesurfaces to^ be joined, interposin a la er of fibrous sheet materialimpregnate wit a binder between said roughened surfaces inserting saidarticles in a press and app ying a temperature which comprisesroughening the surfaces to be joined, interposing a layer of fibroussheet material impre tween said roughene surfaces, inserting said varticles in a press and applying a temperature ranging between 100 and125 C. thereto to form an integral structure.

v11. A method of joining molded articles i which comprises rougheningthe surfaces to be joined, interposing a layer of fibrous sheet materialimpregnated with a binder between said roughened surfaces, insertingsaid articles in a ress and applying a temperature ranging etween and125 C. and a pressure of approximately one-half ton per square inch ofmolding surfaces thereto to form an integral structure.

12. A method of joining a plurality of articlesof fibrous materialconsolidated by a heat-hardened binder which comprises roughening thesurfaces to be joined, interposing a layer of fibrous sheet materialimpregnated with a binder between said roughened surfaces, insertin saidarticles in a press and a plying are atively low temperature and aighpressure thereto to form an integral structure.

13. A method of joining a plurality of articles of fibrous sheetmaterial consolidated by a heat-hardened binder which com risesroughening the surfaces to be joined, Interated with a binder beposing alayeriof fibrous 'sheet material im- 35 pregnated with a binder betweensaid roughened surfaces, inserting said articles in a press and a plyinga temperature below C. and a r atlvely high pressure thereto to form anintegral structure.

14. A method of joining a lurality of articles of fibrous sheet materiaand a phenolic condensation product which comprises roughening t-hesurfaces to be joined, lnterposlng a layerbf fibrous sheet materialimprenated with a binder between said roughene surfaces, inserting saidarticles in a press and applying ate'mperature below a relatively highpressure therel 125 C. and to to form an integral structure.

V15. In the art of joining .a plurality of strip-like members to asheet-bke member,

jthe method which comprises disposing said strip-like members in spacedrelation along said sheet-like member with adhesive material betweenadjacent surfaces thereof, and applying pressure to and elevating thetemperature of said members while maintaining open spaces between saidstrip-like members.

16. In lthe art of joining a lurality 'of strip-like members to asheet-l e member,

the method which comprises disposing .said

sheet-like member with binder-impregnated sheet material betweenadjacent vsurfaces thereof, and applying pressure to and elevating thetemperature of said members.

FRANK H. TUPPER.

str ip-like members in spaced relation along sai

